x86/mm: Extend early_memremap() support with additional attrs

Add early_memremap() support to be able to specify encrypted and
decrypted mappings with and without write-protection. The use of
write-protection is necessary when encrypting data "in place". The
write-protect attribute is considered cacheable for loads, but not
stores. This implies that the hardware will never give the core a
dirty line with this memtype.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Toshimitsu Kani <toshi.kani@hpe.com>
Cc: kasan-dev@googlegroups.com
Cc: kvm@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-efi@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/479b5832c30fae3efa7932e48f81794e86397229.1500319216.git.thomas.lendacky@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/Kconfig

@@ -1440,6 +1440,10 @@ config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
 	  If set to N, then the encryption of system memory can be
 	  activated with the mem_encrypt=on command line option.
 
+config ARCH_USE_MEMREMAP_PROT
+	def_bool y
+	depends on AMD_MEM_ENCRYPT
+
 # Common NUMA Features
 config NUMA
 	bool "Numa Memory Allocation and Scheduler Support"

arch/x86/include/asm/fixmap.h

@@ -164,6 +164,19 @@ static inline void __set_fixmap(enum fixed_addresses idx,
  */
 #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_IO_NOCACHE
 
+/*
+ * Early memremap routines used for in-place encryption. The mappings created
+ * by these routines are intended to be used as temporary mappings.
+ */
+void __init *early_memremap_encrypted(resource_size_t phys_addr,
+				      unsigned long size);
+void __init *early_memremap_encrypted_wp(resource_size_t phys_addr,
+					 unsigned long size);
+void __init *early_memremap_decrypted(resource_size_t phys_addr,
+				      unsigned long size);
+void __init *early_memremap_decrypted_wp(resource_size_t phys_addr,
+					 unsigned long size);
+
 #include <asm-generic/fixmap.h>
 
 #define __late_set_fixmap(idx, phys, flags) __set_fixmap(idx, phys, flags)

arch/x86/include/asm/pgtable_types.h

@@ -161,6 +161,7 @@ enum page_cache_mode {
 
 #define _PAGE_CACHE_MASK	(_PAGE_PAT | _PAGE_PCD | _PAGE_PWT)
 #define _PAGE_NOCACHE		(cachemode2protval(_PAGE_CACHE_MODE_UC))
+#define _PAGE_CACHE_WP		(cachemode2protval(_PAGE_CACHE_MODE_WP))
 
 #define PAGE_NONE	__pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED)
 #define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | \
@@ -189,6 +190,7 @@ enum page_cache_mode {
 #define __PAGE_KERNEL_VVAR		(__PAGE_KERNEL_RO | _PAGE_USER)
 #define __PAGE_KERNEL_LARGE		(__PAGE_KERNEL | _PAGE_PSE)
 #define __PAGE_KERNEL_LARGE_EXEC	(__PAGE_KERNEL_EXEC | _PAGE_PSE)
+#define __PAGE_KERNEL_WP		(__PAGE_KERNEL | _PAGE_CACHE_WP)
 
 #define __PAGE_KERNEL_IO		(__PAGE_KERNEL)
 #define __PAGE_KERNEL_IO_NOCACHE	(__PAGE_KERNEL_NOCACHE)
@@ -202,6 +204,12 @@ enum page_cache_mode {
 #define _KERNPG_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED |	\
 			 _PAGE_DIRTY | _PAGE_ENC)
 
+#define __PAGE_KERNEL_ENC	(__PAGE_KERNEL | _PAGE_ENC)
+#define __PAGE_KERNEL_ENC_WP	(__PAGE_KERNEL_WP | _PAGE_ENC)
+
+#define __PAGE_KERNEL_NOENC	(__PAGE_KERNEL)
+#define __PAGE_KERNEL_NOENC_WP	(__PAGE_KERNEL_WP)
+
 #define PAGE_KERNEL		__pgprot(__PAGE_KERNEL | _PAGE_ENC)
 #define PAGE_KERNEL_RO		__pgprot(__PAGE_KERNEL_RO | _PAGE_ENC)
 #define PAGE_KERNEL_EXEC	__pgprot(__PAGE_KERNEL_EXEC | _PAGE_ENC)

arch/x86/mm/ioremap.c

@@ -417,6 +417,50 @@ void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
 	iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK));
 }
 
+#ifdef CONFIG_ARCH_USE_MEMREMAP_PROT
+/* Remap memory with encryption */
+void __init *early_memremap_encrypted(resource_size_t phys_addr,
+				      unsigned long size)
+{
+	return early_memremap_prot(phys_addr, size, __PAGE_KERNEL_ENC);
+}
+
+/*
+ * Remap memory with encryption and write-protected - cannot be called
+ * before pat_init() is called
+ */
+void __init *early_memremap_encrypted_wp(resource_size_t phys_addr,
+					 unsigned long size)
+{
+	/* Be sure the write-protect PAT entry is set for write-protect */
+	if (__pte2cachemode_tbl[_PAGE_CACHE_MODE_WP] != _PAGE_CACHE_MODE_WP)
+		return NULL;
+
+	return early_memremap_prot(phys_addr, size, __PAGE_KERNEL_ENC_WP);
+}
+
+/* Remap memory without encryption */
+void __init *early_memremap_decrypted(resource_size_t phys_addr,
+				      unsigned long size)
+{
+	return early_memremap_prot(phys_addr, size, __PAGE_KERNEL_NOENC);
+}
+
+/*
+ * Remap memory without encryption and write-protected - cannot be called
+ * before pat_init() is called
+ */
+void __init *early_memremap_decrypted_wp(resource_size_t phys_addr,
+					 unsigned long size)
+{
+	/* Be sure the write-protect PAT entry is set for write-protect */
+	if (__pte2cachemode_tbl[_PAGE_CACHE_MODE_WP] != _PAGE_CACHE_MODE_WP)
+		return NULL;
+
+	return early_memremap_prot(phys_addr, size, __PAGE_KERNEL_NOENC_WP);
+}
+#endif	/* CONFIG_ARCH_USE_MEMREMAP_PROT */
+
 static pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)] __page_aligned_bss;
 
 static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)

include/asm-generic/early_ioremap.h

@@ -13,6 +13,8 @@ extern void *early_memremap(resource_size_t phys_addr,
 			    unsigned long size);
 extern void *early_memremap_ro(resource_size_t phys_addr,
 			       unsigned long size);
+extern void *early_memremap_prot(resource_size_t phys_addr,
+				 unsigned long size, unsigned long prot_val);
 extern void early_iounmap(void __iomem *addr, unsigned long size);
 extern void early_memunmap(void *addr, unsigned long size);
 

mm/early_ioremap.c

@@ -226,6 +226,16 @@ early_memremap_ro(resource_size_t phys_addr, unsigned long size)
 }
 #endif
 
+#ifdef CONFIG_ARCH_USE_MEMREMAP_PROT
+void __init *
+early_memremap_prot(resource_size_t phys_addr, unsigned long size,
+		    unsigned long prot_val)
+{
+	return (__force void *)__early_ioremap(phys_addr, size,
+					       __pgprot(prot_val));
+}
+#endif
+
 #define MAX_MAP_CHUNK	(NR_FIX_BTMAPS << PAGE_SHIFT)
 
 void __init copy_from_early_mem(void *dest, phys_addr_t src, unsigned long size)